1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to an optical lens and a manufacturing method thereof, and more particularly, to an optical lens which changes a focus due to a change in a shape of a translucent elastic membrane according to a change in a pressure in a lens chamber, and a manufacturing method thereof
2. Description of the Related Art
In general, an optical lens is a transparent element or a lens that has at least two refraction curves. Such an optical lens has been widely used in various fields of the real life, for example, in various cameras, telescopes and microscopes.
For example, a camera module using the optical lens is applied to a personal mobile terminal such as a mobile phone or a PDA in addition to a camera set itself Recently, the personal mobile terminal has been developed to a multi-purpose electronic device that has a variety of multimedia functions (e.g., camera, game, music, broadcast, and internet) in addition to a simple voice sending and receiving function, and, with this development, there has been an attempt to integrate more functions into a limited space.
Also, a recently developed camera module has advanced functions such as an auto focusing, an auto zooming, and an auto macro to be able to obtain a high quality of image, in addition to a basic function of a camera. However, if the camera module is to be mounted on a personal mobile terminal, there is a problem in reducing the size of the camera module because a size of a lens and a physical size of a mechanical lens driving device should be large sufficiently to have the advanced functions.
That is, in order to realize the advanced functions, various types of lenses such as a close-up lens, a normal lens, a telephoto lens, and a zoom lens should be provided and replaced according to a user's purpose. Also, in order to realize an auto focusing, an optical property (focal distance) of the lens should be variable, and an extra motor or driver is required to adjust this variation. Therefore, the whole size of the camera module inevitably increases.
To this end, a liquid lens or a fluid lens using an electrowetting phenomenon has been suggested.
The liquid lens performs an auto focusing and a zooming using a curvature variation of the lens. The liquid lens uses an electrowetting phenomenon to cause the curvature variation. The electrowetting is to control a surface tension of a conductive fluid by applying a voltage to an electrode coated with an insulating material and the conductive fluid when the conductive fluid and a non-conductive fluid come in contact with each other on the electrode and thus change a contact angle of the conductive fluid and an interfacial shape between the two fluids. This electrowetting has an advantage in reducing the size of the camera module because there is no mechanical lens movement.
Also, there has been an optical lens that is capable of auto focusing and zooming by changing a pressure exerted to an optical fluid contained in a lens chamber and thus changing a curvature of a translucent elastic membrane formed in the lens chamber. Such type of optical lens has a simplified structure and a simplified manufacturing process. Accordingly, the optical lens is easy to produce and also is of benefit to a mass production because it can be manufactured in a wafer level.